With the equipment you are looking at , top of the line and all the
extras there is alot more to break, get the 10 yr full warranty, a VS DC
motor may be a 600 $ replacement.
You are looking at two stage gas, right. Carrier Mvp has a 49000 low
fire 75000 high fire model, a 61000 low fire-93000 high fire Btu model
and a 73000 low fire- 113000 high fire model . I dont know if these are
input or output ratings, I believe output . The 70000 Btu he gave you
is what you will need at the coldest temps. And is probably input btu.
with a VS 2 stage you only need the high fire in cold weather, or for
recovering from setback temps. You can use the 49000- 75000 unit, or
maybe even a smaller one if theses are output figures. Dont oversize,
you will get more even heat with a smaller unit, and short cycle less.
My unit is oversized and the second stage is only used to recover from
set back temps, not in normal operation. My next replacement will be a
size smaller in Btu.
AC Compressors- heat pumps, have Db sound ratings from the factory, a
standard is at 3 ft for testing, check ratings and at what distance the
testing was done.
Either way both units are good, so it is up to a real good instaler to
get you the right unit and proper instal.